Sealants useful in aerospace and other applications must satisfy demanding mechanical, chemical, and environmental requirements. For example, it is desirable that aerospace sealants function over a temperature range such as from about −67° F. to about 360° F. and exhibit fuel resistance. As disclosed in U.S. application Ser. No. 13/923,903 and U.S. application Ser. No. 13/923,941, sealants formed using polythioether prepolymers having bis(sulfonyl)alkanol groups incorporated into the backbone and/or present as terminal groups exhibit enhanced adhesion to metal surfaces and meet other performance requirements for aerospace sealants.
Aerospace vehicles often include lightweight surfaces made from aluminum and titanium alloys. Previous work by the inventors demonstrated that compositions having improved adhesion to these surfaces could be realized by using prepolymers in which a bis(sulfonyl)alkanol moiety was incorporated into the backbone of the prepolymer. Expanding this work to include other metal ligands provides additional opportunities for enhancing surface adhesion to aerospace and other surfaces.
Sulfur-containing prepolymers having improved adhesion to metal surfaces and that meet other performance requirements for use in aerospace and other applications are desired.